how the fbi, which interviewed tamerlan in 2011, lost track of him. what we have learned, the fbi database did not catch that trip to russia, that important trip where he reportedly became radicalized. officials here in washington say his name was misspelled on a flight manifest and fell through the cracks. they're determined to prevent that from happening again. john and diana? >> devin dwyer from washington. thank you. >>> another person who may be able to shed some light on the plot, the older brother's widow. the fbi wants to question katherine russell and her attorney. a meeting is being arranged. so far, she says she had no idea about her husband's deadly plot. and investigators are looking at whether tamerlan was involved in the brutal murder of three young men in 2011. one of whom was his roommate. the three young men were found with their throats slashed. >>> authorities in canada have foiled a plot to unleash terror on hundreds of unsuspecting train passengers. two men under arrest for planning the attack were allegedly getting direction and